IAB's are typically employed for assisting a weakened heart in performing its pumping function. IAB's are preferably inserted percutaneously. In order to facilitate percutaneous insertion, at least the balloon portion of an IAB is adapted to be wrapped about itself or about a stylet extending through the balloon to reduce the profile of the balloon at least during insertion and positioning thereof. Once the balloon is inserted, means are typically provided for untwisting or unwrapping the balloon to permit balloon pumping.
The unwrapped balloon is coupled to a source of pressure capable of periodically inflating and deflating the balloon in a particular timing relationship with the weakened heart to assist the heart in its pumping function. During one phase of balloon pumping, a vacuum is drawn upon the balloon causing the balloon to deflate and substantially fully collapse. Although it is extremely desirable to have the balloon collapse over substantially its entire length, it is possible that the balloon will partially collapse. For example, it is possible that the proximal end of the balloon will collapse so completely as to prevent the portion of the balloon between the distal end and the point of collapse from deflating fast enough for adequate synchronization with the heart's contraction. This condition will slow down passage of blood in the region of the aortic arch where the inflated portion of the balloon is positioned, seriously interfering with the pumping function of the heart, compromising the benefits of the balloon, and potentially causing great harm to the patient.